The embodiments herein relate generally to audio speaker systems and, in particular, systems for processing signals from an audio source and directing those processed signals to a plurality of loudspeakers to reproduce high quality stereophonic sound.
By way of background, loudspeakers include electromechanical transducers that convert electrical signals into sound. Audio sources (e.g., stereo systems) typically generate stereophonic sound in the form of separate signals reflecting a left channel (L) and a right channel (R) that are used by electrically connected loudspeakers to generate sounds associated with the left and right channels. To reproduce stereophonic sound in a pleasing manner to listeners within the ambient of the audio source and loudspeakers, a conventional stereo system is typically placed such that at least one loudspeaker reproducing left channel sound is positioned to the left of the listener, while at least one other loudspeaker reproducing right channel sound is positioned to the right of the listener. Other loudspeakers may be employed with audio sources, such a center speakers that combine left and right channel signals or have a dedicated center channel signal, additional left and right channel loudspeakers positioned as a pair in a forward and a rearward position, and a subwoofer to which low frequency signals are parsed from the audio source and reproduced by the subwoofer to present the low bass sounds for the listener.
In many environments, the proper placement of loudspeakers can be difficult to achieve because the sounds reproduced by the plurality of speakers cross paths and, indeed, often interfere with each other. For example, in a portable electronic device, the left loudspeaker and the right loudspeaker may be placed so close together that the resulting stereo separation is inadequate. In another example with separate left and right loudspeakers, space on a countertop or a desktop may be too limited for relatively good placement of the loudspeakers, and in both examples best fidelity is achieved at only one listening position, usually directly in front of and centered between the left and right loudspeakers. In addition, many people do not possess the expertise necessary to position separate loudspeakers for relatively good sound field reproduction.
Many surround-sound systems reflect expertise in loudspeaker layout to minimize interference and maximize robust quality of sound. One desirable result is the reduction in the discernable detection of the point source of sound reproduction; i.e., detection from where the sound is specifically coming. There is a desire among audiophiles to present stereophonic sound reproduced seamlessly throughout the environment, while still detecting the high, medium and low frequency qualities of the sound output.
One problem faced by system designers is providing broad and robust sound where the speakers are presented in a compact, single-body environment, such as a sound bar. The close proximity of the speakers tends to present narrower sound fields, which come across as less robust, and less distinguishable vis-à-vis the variety of frequencies in audio. In other words, less sound separation is achieved. Indeed, the inventor of the present embodiments herein described efforts at addressing this particular problem, presenting meaningful embodiments in U.S. Pat. No. 8,175,304 to North, the contents of which are incorporated herein by reference. Indeed, reference is made to FIG. 1 of this patent, which excerpts FIG. 4 from the '304 patent. Embodiments of the present invention herein also address at least some of the difficulties in satisfying the desire for broad field sound emanating from compact speaker environments.